Okay guys I did my own rebuild the only part I didn't do was set the ring and pinion. I did rebuild the posi myself I purchased the new oversized cones from Glenn at 9bolt.com for 132.00 USD. I then took the posi halves and ground down the inner raised ring portion flat. That allows much more room so the new cones don't bottom out from what Glenn and I discussed the m78 in the US is their 2nd generation they're now on there 4th gen solid diff 5th gen in our GTO/Holden I.R.S also called a M80 i.r.s parts from the M76/M77/M78 all are interchangeable. That means any car from Australia with a M76 M77 M78 ring and pinion will fit our cars and there are a lot the skyline GTR, the Ford turbo Falcon, all LS engine Holden's. So when people say that the 10 bolt is as strong as a 9 bolt they're sadly mistaken you can watch Australian Godzilla GTR's running 8 second quarter mile times in factory 9 bolt Nissan Skyline with a 2 SERIES CARRIER. So I said all that to say this it is well worth it if you are good with your hands to rebuild the 9-bolt and now there is a Detroit true track offered for the 9-bolt under 500 dollars. And easily installed. So if you can't afford an expensive diff roll up your sleeves and put in the work it's well worth it and if you have questions ask me or contact Glenn at 9-bolt.com he has been doing a bunch to upgrade his website since he took it over from the last guy

 

Is 85w140 good to use in this rear? with the friction modifier...

 

Torco is the best oil to use in the 9 bolt, but others work. Most of the time the additive is needed.

 

Where can you source the Detroit truetrac in the US? It's not showing up in any search.

 

From others input here, you have to get it from Australia, it's not an ACTUAL Detroit/Eaton piece, it's just a helical gear diff

 

Contact Dave at Supa-F Spares in Australia. He can get you one. You want the Torsen carrier for the Holden Commodore VL.

GD